1. Field of the Invention
The present invention relates to an electrophotographic printer, and more particularly, to an electrophotographic printer capable of preventing sticking of toner on the surface of a drying roller during the step of firmly adhering a developed image on a photosensitive medium, thereby improving print quality.
2. Description of the Related Art
FIG. 1 is a diagram schematically showing the structure of a conventional electrophotographic printer.
As shown in FIG. 1, the conventional electrophotographic printer includes a photosensitive belt 10 making a circular movement and three rollers including first, second and third rollers 21, 22 and 23 which are fixed at predetermined positions, to circulate the photosensitive belt 10 in a closed circuit. The third roller 23 is a driving roller for driving the photosensitive belt 10 by a driving force of a driving motor (not shown) and the second roller 22 is a steering roller for preventing slanted traveling by controlling the tension of the photosensitive belt 10. A drying roller 50 for drying a developing solution adhered to the photosensitive belt 10 while pressing the photosensitive belt 10 against the third roller 23 is placed near the third roller 23. Also, a transfer roller 24 is placed next to the first roller 21. An image formed on the photosensitive belt 10 is transferred to the transfer roller 24 as it rolls along the photosensitive belt 10. A pressing roller 25 is for transferring the image transferred onto the transfer roller 24 on a printing paper 60 by pressing the printing paper against the transfer roller 24. The pressing roller 25 is installed near the transfer roller 24.
At one end of the photosensitive belt 10 between the first and second rollers 21 and 22, is an eraser 34 for erasing an electrostatic charge of an electrostatic latent image remaining on the surface of the photosensitive belt 10. A main corona device 35 is placed next to the eraser 34, for electrifying the charge on the photosensitive belt 10 to a predetermined level such that the developing solution is developed.
Below the photosensitive belt 10, is a plurality of laser scanning units (LSUs) 30 for forming an electrostatic latent image by irradiating laser beams on the photosensitive belt 10 according to an image signal, and a plurality of developing units 40 alternating with the LSUs 30 for developing the electrostatic latent image by supplying a developing solution containing toner with a predetermined color to an area having the electrostatic latent image.
In the electrophotographic printer having the above structure, each LSU 30 forms an electrostatic latent image by irradiating light on the conveyed photosensitive belt 10. The developing units 40 provide the developing solution to the photosensitive belt 10 having the electrostatic latent image to form a color image corresponding to the electrostatic latent image. The area of the photosensitive belt 10 in which the color image is formed is pressed and heated by the drying roller 50 while passing the drying roller 50. As a result, a carrier is removed from the developing solution that forms the color image. The color image formed on the photosensitive belt is transferred onto the transfer roller 24, and the image transferred onto the transfer roller 24 is transferred again onto the printing paper 60, which enters between the transfer roller 24 and the pressing roller 25, thereby completing the printing of an image onto the printing paper 60.
In the printer having the above structure, when the drying roller 50 presses the photosensitive belt 10 in order to remove carrier from the developing solution, toner contained in the image sticks to the drying roller, thereby lowering the quality of the image printed on the printing paper 60.